Usually I use an EQ, if the vocals are already warm usually I use the Waves q6, if the vocals need more prominence i use URS Eq's (using a high pass filter or cutting low end with 1/3 band eq up to around 80-120 ) Then I usually compress with eithor Waves SSL plugin, Waves Rcomp, Urs Comps and push it fairly hard (usually with a ratio of 2.5 to 4 with a slow attack (around 120ms) and a quick release (usually around 20-40ms) and a Make up gain between 1-6db. If needed I will use another EQ, Usually Waves Q10 if to correct any imperfections without adding much color. On the end i will usually ad a convoloution reverb like waves IR-1 with a studio or hall verb, filtering out the low end and high end above 4-6k, I usually cut the reverb time very short between 4ms and 40ms and just add a touch of wetness to the mix..usually between .20 and .50 ms...(I listen for when the vocals seem to jump out of the speakers (3D).

Thats for the Main vox...

As far as stacks/backups....similar but different...

heres my chain...

Blue tubes stereo widener, EQ (high shelf, cut up to about 125-500hz), Compressor (usually psp vintage warmer, or waves rcomp), then usually a chorus or delay with a very small delay time(or waves doubler), then an overall eq to assist the main vocal in thickness and clarity by adding high end and low mids.